Asymmetries in Motile Responses of Outer Hair Cells in Simulated in Vivo Conditions
It is now well known that electrical stimulation of isolated mammalian outer hair cells results in a motile response (Brownell, 1983;Ashmore,1987;Zenneret al.,1987). The fast response component is apparently capable of following a sinusoidal current stimulus in the audio frequency range (Ashmore, 1987; Zenner et al., 1987). Fast motility is a robust response that has been shown under conditions that are distinctly non-physiological. In all experiments reported thus far, all cell surfaces were bathed in a high-sodium medium. Of course, under in vivo conditions only the basolateral cell membrane is exposed to perilymph (high Na+) while the hair-bearing apical end is bathed in endolymph (high K+). We demonstrate here that isolated cells show two kinds of rectification in their motility with sinusoidal current stimuli, that there are quantitative differences in the responses as a function of cell length, and that these phenomena persist when the apical and basolateral cell surfaces are exposed to their proper biochemical environment.
KeywordsFast Motility Outer Hair Cell Response Component Basolateral Cell Membrane Basolateral Cell
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